Traditionally, vacuum cleaners having power heads with a rotatable brush have been required to clean surfaces having both deep carpet and bare floors. Therefore it is necessary that this rotatable brush be capable of movement with the nozzle between various selected nozzle heights above the surface to be cleaned. For deep carpet surfaces, the nozzle is positioned at a high elevation relative to the surface to be cleaned and for bare floors, the nozzle is positioned at a low elevation relative the surface to be cleaned.
When cleaning bare floors the friction between the rotatable brush and the floor as a result the cleaning ability of the vacuum cleaner is diminished. The spacing of the base of the vacuum cleaner relative to the bare floor allows large particles of debris to be thrown backward by the rotatable brush at a speed which is too quick for the suction created by the nozzle to carry these particles into the nozzle.
Various attempts have been made to alleviate this problem. Initially, a flexible but fixed contact strip was utilized behind the rotatable brush to prevent the debris from travelling backward behind the nozzle. Examples of such an approach may be seen in U.S. Pat. Nos. 1,288,028 and 1,288,029.
Thereafter, a trailing brush was introduced which was movable between a retracted position within the head assembly and an extended position adjacent the bare floor. This approach utilizes various methods of extending and retracting the trailing brush. In all these approaches, the trailing brush is movable between the extended and retracted positions independent of the height of the head assembly. U.S. Pat. Nos. 4,014,068 to Payne et al., 4,073,031 to Schwartz, and 4,109,342 to Vermillion disclose approaches which rely on a foot or hand pedal to move the trailing brush between the retracted and extended positions.
The present invention is directed to improving known retractable trailing brush technology for use on bare floors by a vacuum cleaner. The present invention is directed to combining the operation of the height adjustment mechanism of a vacuum cleaner and the retractable trailing brush.